Synthetic products of high molecular weight



United States Patent SYNTHETIC PRODUCTSOF HIGH MOLECULAR WEIGHT Karl E. Miiller, Leverkusen, Germany, assignor to Farbenfabriken Bayer Atkiengesellschaft, Leverkusen, Ger many, a corporation of Germany No Drawing. Application April 21,1954 Serial No. 424,760

Claims priority, application Germany April 23, 1953'- Claims. (Cl. 260-45.4)

This invention relates to synthetic. polymeric roduct's offhigh molecular Weight and to a process for their pro duction. The purpose of this invention is to provide an improved process for the production of diisocyanatemodified polyesters which can be handled in the liquid phase.

It is known to produce cross-linked polymeric products by reacting linear polyesters containing hydroxyl end groups with a quantity of organic diisocyanates in excess of the amount required to react with the hydroxyl groups. In this reaction the polyester chains become linked by urethane groups to form linear compounds containing frlee isocyanate end-groups. The molecular Weight of these linear isoc anate-modified polyesters increases'as the excess of diisocyanate over the quantity required for reaction with the hydroxyl groups decreases, or vice Versa. The i'socyanate-modified polyesters thus obtained can, be converted to high grade cross-linked products according to the process described in our copending a plication Ser. No. 70,598, filed January 12, 1949, by Karl Erwin Miiller, Hans-Frank Piepenbrink, Friedrich Wilhelm Schmidt and Erwin Weinbrenner and which has now become abandoned; This process consists in reacting the isocyanate-modified polyesters with glycols, whereby the polyester chains are linked by urethane groups and. thus increased in length, and then further isocyanate groups. react with the hydrogen atoms of these resultant urethane roups to give cross-linking in the molecule. This reac-' tion can beaccelerated by the addition of tertiary bases, such as hexahydrodimethyl aniline, or retarded by the addition of acids. Since the tertiary bases do not contain These glycols which are incorporated into the molecule to exert an acceleratingorretarding'action on the above said reaction can also be employed in mixture or-in combination with unsubstituted glycols; for instance butane diol, quinitol or diethylene glycol. It is possible to com trol and vary the mechanical propertiesof the final products substantially by using appropriate combinations ofglycols. The reaction according to: the invention: prodeeds, as does the above-describedknownprocess; Without the evolution of carbon dioxide, and. can-therefore be conducted in the liquid phase.-

The process of the invention can be carried out by reactingthe above-defined glycols with the isocyanate-modified olyesters. The quantitative proportions ofthe re.- actanfs are preferably so chosen that: the NCO-groups remain inslight excess, by'nsing an amount of the glycols slightly less than the stoichiometrical roportion.

According to another-1' embodiment of' the invention the glycols are incorporated into the polyeste by stirring andreacted with the diisocyanatesin a second stage. In. this embodiment the components-are again employed. in" the above-said quantitative proportions; The CIOSSHDk ing can then take lace while the mixture is being'moulded,

Alternatively, the glycols are employed in a proportion equivalent to the isocyanate groups'pre'sent in the iso cyanate-modified polyester and l-5% of a diisocyanate incorporated into thc linear compounds-so obtained prior to'm'ouiding. v w

Suitable diis-ocyanates for-the process-:ofthe invention are for instance diphenylrnethane diisocyanate, I,5-naphthalehe diisocyanate and p phenyl" diisocyanat'e.

The preferred linear polyesters employed as starting materials are those prepared from suhstantiallysatnrated aliphatic roducts. Suitable acid components are adipic acid, succinic acid, sebacic acid and thiodipropionic acid. The polyestermay have. incorporated thereinsmaller proportions. of: aromaticv dicarboxylic acids, for instance phthalicv acid. Suitable glycol components. ofthe'polyesters are for instance ethylene glycol, 1,4=butylene'glycol, and. diethylene. glycol- Care must betaken that, owing.

to. a slightexcess of. glycolsand to. sufiiciently longrheab' functional groups they are present in. the resultantprod- 1 not as plasticizers and can be extracted therefrom, for instance by means of solvents.

In accordance with the invention it has been found,

that the velocity of the afore-described reaction of the mechanical properties, glycols of weakly basic character,

which are obtainable by known methods by reacting two mols of ethylene oxide and 1 mol of an aromatic amine, have proved to be particularly suitable according to the invention.

Suitable amines for the herein described process are dihydroxyethyl aniline, substitution products thereof, and dihydroxyethyl naphthylamine; examples of compounds having a stronger basic nature are dihydroxyethyl cyclohexylamine and methyl diethanolamine.

Products containing groups which delay the reaction of the isocyanate-modified polyesters are glycols containing halogen-, cyanoor nitro-groups. As examples may be mentioned uor fl-chlorohydrin, and the glycols containing nitro groups which are obtained by the reaction of formaldehyde with hydrocarbons containing nitro groups.

mg, the polyester has. practically no: acid-value; The OH-value must be between; about 20 and about 80, preferably between 40 and 60. That corresponds to a percentage of OH-groups of 0.6-2.4, preferably 122 4.8 by weight. Other hifunctionali com onents may be added in minor quantities to. replace part of" the said dicarboxylic acids and glycols; Examples of such components are diamines, hydroxyamines and glycols, which contain. groups which are capable of accelerating or retarding, the reaction of the isocyana'te-modified polyester.

x The present'invention is further illustrated by the following examples.

Example I- 1 kilogram of a glycol adi ic acid ester of hydroxyl number 55 and acid number 1 is dehydrated at -1309 (3.; ilndl 12 millimeter pressure, and IJOI'gIanis of I,5-naphthylene 'diiso'cyanat'e are introduced with stirring; the temperature rising to 138 C. After cooling the melt to C., 51.5 grams of dihydroxyethyl-a-naphthylamine are introduced with stirring, and the mixture is cast into moulds and heated to 100 C. for 35 hours. A highly elastic material with the following properties is obtained:

3 Example The same starting materials and proportions as in Example 1 are used, but the dihydroxy-ethyl-a-naphthylamine is introduced with stirring into the dehydrated polyester, and the 1,5-naphthylene diisocyanate is reacted in a second stage. A highly elastic material with the following properties is obtained:

2 kilograms of a glycol adipic acid polyester of hydroxyl number 56 are dehydrated, and 274 grams of 1,5-naphthylene diisocyanate added with stirring. After the temperature of the melt has dropped from 140 C. to 130 C.', 80 grams of dihydroxyethyl-a-naphthylamine (this quantity is equivalent to that of the diisocyanate groups) are added with stirring, and the mixture is made into a sheet on the roller after condensation at 100 C. 100 grams of 1,5-naphthylene diisocyanate are incorporated on the roller, and a sheet is obtained which gives excellent, highly elastic plates with good mechanical properties after pressing.

Example 4 To 1 kilogram of a dehydrated glycol adipic acid polyester of hydroxyl number 56 and acid number 1 are added with stirring at 130 C. 170 grams of 1,5-naphthylene diisocyanate. After the temperature has dropped to 130 C. a mixture of 15' grams of butanediol and 10 grams of dihydroxyethylcyclohexylamine is added with stirring. By casting the melt into moulds and heating at 100 C.

for 24 hours a highly elastic material with the following properties is obtained: 7 Y Tensile strength kg./cm. 239

Elongation at break percent 565 Permanent set do 7 Tear resistance do 22 Resilience 48/64 1 Hardness 74 57 Load at 300% elongation 0 Example 5 200 grams of a glycol adipic acid polyester of hydroxyl number 56 are dehydrated and reacted with 34 grams of 1,5-naphthylene diisocyanate. After the temperature has dropped to 130 C., Sgrams of a-chlorohydrin are added. The melt is cast into moulds and heated to 100 C. for 48 hours.-- The material thus obtained has the following mechanical properties:

Tensile strength kg./cm. 277 Elongation at break "percent-.. 720 Permanent set rln 3 Tear resistance dn Resilience 45 4 Hardness 60/61 Load at 300% elongation--.... 31

When the a-chlorohydrin in the above reaction is replaced by 6.6 grams of 2-nitroethyl-1,3-propanediol of the following formula:

the other quantitative proportions remaining the same, a product with similar mechanical properties is obtained.

I claim:

1. In a process of forming a high molecular weight cross-linked polymer by reacting an organic diisocyanate with a cross-linking glycol and an anhydrous organic linear polyester having from 0.62.4% by weight of hydroxyl groups and an acid value substantially not exceeding 1, said polyester being prepared substantially from an aliphatic dicarboxylic acid and an aliphatic glycol, the improvement comprising employing as the cross-linking glycol in the formation of said cross-linked product one which will accelerate the cross-linking reaction, said glycol containing a tertiary nitrogen atom and being selected from the group consisting of dihydroxyethyl aniline, dihydroxyethyl naphthylamine, dihydroxyethyl cyclohexylamine, and methyl diethanolamine.

2. Process of claim 1 wherein the cross-linking glycol is stirred into the polyester, and the organic diisocyanate is reacted in a second stage.

3. A process for the production of a high molecular weight cross-linked polymer which comprises reacting an anhydrous organic linear polyester having from 0.6-2.4% by weight of hydroxyl groups and an acid value substantially not exceeding 1, said polyester being prepared substantially from a saturated aliphatic dicarboxylic acid and an aliphatic glycol, with an organic diisocyanate in stoichiometric excess of the quantity required to react with the end groups of the polyester, and then reacting the resulting isocyanate-modified polyester with a glycol containing a tertiary nitrogen atom and selected from the group consisting of dihydroxyethyl aniline, dihydroxyethyl naphthylamine, dihydroxyethyl cyclohexylamine, and methyl diethanolamine, said glycol having the property of functioning as an accelerator for the cross-linking reaction, the resulting cross-linked polymer being free from the disagreeable odor characteristic of free tertiary amines.

4. Process of claim 3 wherein the glycol is employed in an amount slightly less than the stoichiometric proportion required to react with the NCO groups of the diisocyanate-modified polyester.

5. Process of claim 3 wherein the diisocyanate, is 1,5-naphthylene diisocyanate and the cross-linking glycol is dihydroxyethyl naphthylamine.

References Cited in the file of this patent UNITED STATES PATENTS 

1. IN A PROCESS OF FORMING A HIGH MOLECULAR WEIGHT CROSS-LINKED POLYMER BY REACTING AN ORGANIC DIISOCYANATE WITH A CROSS-LINKING GLYCOL AND AN ANHYDROUS ORGANIC LINEAR POLYESTER HAVING FROM 0.6-2.4% BY WEIGHT OF HYDROXYL GROUPS AND AN ACID VALUE SUBSTANTIALLY NOT EXCEEDING 1, SAID POLYESTER BEING PREPARED SUBSTANTIALLY FROM AN ALIPHATIC DICARBOXYLIC ACID AND AN ALIPHATIC GLYCOL, THE IMPROVEMENT COMPRISING EMPLOYING AS THE CROSS-LINKING GLYCOL IN THE FORMATION OF SAID CROSS-LINKED PRODUCT ONE WHICH WILL ACCELERATE THE CROSS-LINKING REACTION, SAID GLYCOL CONTAINING A TERTIARY NITROGEN ATOM AND BEING SELECTED FROM THE GROUP CONSISTING OF DIHYDROXYETHYL ANILINE, DIHYDROXYETHYL NAPHTHYLAMINE, DIHYDROXYETHYL CYCLOHEXYLAMINE, AND METHYL DIETHANOLAMINE. 